本程序集对地球物理场做多种处理 如：2阶及4阶导数，位场转换，不规则密度体重力场计算，竖直圆柱体重磁场计算，用泰勒多项式及最小平方2乘的剩余异常计算，（主要适用于地磁场以及重力场的转换）-FUNCTION : THIS ROUTINE IS USED TO CALCULATE GRAVITY FOR VARIABLE　　 DENSITY OF 2D BIVARIATE TRAPEZOID BODY　

Function : This program calculate derivation of order 2 and order 4 uesd in Geophysical Field（magmagnetic，gravity field）

FUNCTION : THIS ROUTINE IS USED TO CALCULATE GRAVITY FOR VARIABLE DENSITY OF 2D BIVARIATE TRAPEZOID BODY　

Purpose:　 Continuation of potential fields (upward and downward continuation )　　

Function:　 This program will calculate residual anomaly,